Daiichi Sankyo is shutting down (PDF) its Plexxikon R&D operation in South San Francisco. More than 10 years after buying the biotech for $805 million upfront, Daiichi has decided to drop the 60-employee operation to focus investment on three antibody-drug conjugates (ADCs).
Plexxikon retained its own brand, leadership team and pipeline after being acquired by Daiichi in 2011. Working out of its West Coast base, the biotech went on to deliver two FDA-approved oncology drugs: a treatment for rare benign tumors, Turalio, and the Roche-partnered melanoma drug Zelboraf. With a few candidates in phase 1 and more prospects in preclinical, Plexxikon was looking to repeat its successes.
Daiichi’s focus has shifted, though. Today, Daiichi sees its two AstraZeneca-partnered ADCs, Enhertu and datopotamab deruxtecan, along with the wholly owned patritumab deruxtecan as the priority programs. The three ADCs form one of the four strategic pillars in Daiichi’s five-year business plan.
That thinking has left Plexxikon and its structure-guided, small-molecule oncology drugs out in the cold. Daiichi is set to shutter the subsidiary by the end of March. Plexxikon’s pipeline programs will transfer to Daiichi, but the site and its 60 employees are no longer part of the Japanese drugmaker’s plans.
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Plexxikon survived waves of restructuring by Daiichi in the decade after the takeover, when other R&D units in locations including Germany and India got the chop. However, the reorientation of Daiichi R&D around its three ADCs has delivered the killer blow to the operation in California.
The ADCs are now critical to the midterm success of Daiichi. While Enhertu is already approved in some indications, Daiichi foresees a significant expansion of its commercial ADC portfolio. By 2025, Daiichi is aiming to have expanded the Enhertu label to cover more indications and to have received approvals for the other two ADCs in non-small cell lung cancer.